The present invention relates to equipment for desalination of water by reverse osmosis which allows energy recovery through various solutions and related variants.
It is known that the filtration of a liquid by reverse osmosis requires the use of high pressures and that the conventional equipment used therefore, producing high pressures by means of a high pressure pump and a throttle valve, has low energy efficiency.
The main object of the present invention is to provide equipment for desalination of water by reverse osmosis whereby an energy saving is achieved.
In a first solution, the high pressure needed for the reverse osmosis process is achieved through a device able to hydraulically amplify the pressure provided by low pressure pumps.
Therefore, this equipment doesn""t need the high pressure pumps of a conventional reverse osmosis system, but can make use of low pressure pumps, suitably connected to a pressure amplifier (described hereinbelow) as well as to the reverse osmosis membranes.
The energy saving is thus achieved through the considerable reduction of the system feeding pressure, which is amplified by a passive amplifying device.
In a second solution, the high pressure needed for the reverse osmosis pressure is achieved through a conventional high pressure pump.
However, the flow rate of this pump is not equal to the total flow rate of the water to be treated, as in the conventional systems, but is only equal to the flow rate of fresh water produced by the system.
This is achieved through a hydraulic device (described hereinbelow) which forms a closed circuit between the inlet and the outlet of the reverse osmosis membrane, allowing a fresh water production equal to the flow rate provided by the high pressure pump.
The energy saving is thus achieved through the considerable reduction of the flow rate of the high pressure pump for feeding the system.
The present invention also involves various switching systems or the cycle reversal valve as well as arrangements for further increasing the working flexibility of the system.